U.S. patent number 5,938,389 [Application Number 08/900,564] was granted by the patent office on 1999-08-17 for metal can and method of making.
This patent grant is currently assigned to Crown Cork & Seal Technologies Corporation. Invention is credited to Nasr Habib Hanna, Sudesh Kumar Nayar, Zeev W. Shore.
United States Patent |
5,938,389 |
Shore , et al. |
August 17, 1999 |
**Please see images for:
( Certificate of Correction ) ** |
Metal can and method of making
Abstract
A method of making a non-cylindrical shaped metal can that is
provided with a stylized, irregular shape includes steps of forming
a substantially cylindrical sidewall portion (12) that has a
plurality of ribs integrated therein. These ribs provide additional
strength to the sidewall portion. The cylindrical sidewall portion
may then be shaped into a non-cylindrical, stylized shape. The ribs
(26) are preferably positioned at portions of the shaped sidewall
portion (12) that are anticipated to need increased strength in
order to withstand deformation under pressure. The sidewall (12) is
then assembled to at least one can end member (30) to form a
completed shaped metal can (28). The ribs may either be arranged
longitudinally, circumferentially, or both may be provided to form
a grid structure.
Inventors: |
Shore; Zeev W. (Hazel Crest,
IL), Nayar; Sudesh Kumar (Wiltshire, GB), Hanna;
Nasr Habib (Oxfordshire, GB) |
Assignee: |
Crown Cork & Seal Technologies
Corporation (Alsip, IL)
|
Family
ID: |
21812770 |
Appl.
No.: |
08/900,564 |
Filed: |
July 25, 1997 |
Current U.S.
Class: |
413/2; 220/673;
413/69; 413/76 |
Current CPC
Class: |
B65D
1/165 (20130101); B21D 51/2646 (20130101); B65D
1/44 (20130101); B21D 22/28 (20130101) |
Current International
Class: |
B21D
22/28 (20060101); B21D 51/26 (20060101); B21D
051/26 () |
Field of
Search: |
;413/2,76,69,71,55,32
;220/673,672,671,670,669 |
References Cited
[Referenced By]
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Other References
Frederic Swing Crispen, C.E. "Dictionary of Technical Terms" Bruce
Publishing p. 16 (1946)..
|
Primary Examiner: Coan; James F.
Attorney, Agent or Firm: Woodcock Washburn Kurtz Mackiewicz
& Norris LLP
Parent Case Text
This application claims .sctn.119(e) priority based on provisional
application 60/023,039, filed on Aug. 2, 1996.
Claims
What is claimed is:
1. A method of making a non-cylindrical shaped metal can body that
is provided with a stylized shape, comprising:
(a) forming a substantially cylindrical sidewall portion having at
least one circumferentially extending rib integrated therein, said
rib providing additional strength to the sidewall portion; and
(b) thereafter expanding the cylindrical sidewall portion into a
non-cylindrical, stylized shape, and wherein said ribs are
positioned at portions of said expanded sidewall portion that are
anticipated to need increased strength, whereby said expanded
sidewall portion is reinforced without increasing overall thickness
of the sidewall.
2. A method according to claim 1, further comprising a step of:
assembling at least one can end member to said shaped sidewall
portion, thereby forming a completed shaped metal can.
3. A method according to claim 1, wherein step (a) comprises a
drawing and ironing process that is performed with a punch that has
at least one circumferential groove therein corresponding to said
circumferentially extending rib(s).
4. A method according to claim 1, wherein step (a) further
comprises forming at least one rib in said sidewall portion that is
not fully circumferential.
5. A method according to claim 1, wherein step (a) further
comprises forming a plurality of substantially longitudinally
extending ribs integrally into the sidewall, said longitudinal and
circumferential ribs thereby forming a gridwork of reinforcing
cells in the sidewall portion that will enhance column strength,
hoop strength, crush strength and pressure strength.
6. A method according to claim 1, wherein there are a plurality of
said circumferential ribs.
7. A method according to claim 1, wherein said circumferentially
extending rib is formed by an area of increased thickness in said
sidewall.
8. The method of claim 1 wherein the step of expanding comprises
creating a positive pressure differential between the interior of
the can body and an external environment.
9. A can made according to the method described in claim 1.
10. A method according to claim 7, wherein said thickened
circumferentially extending rib projects radially inwardly from
said sidewall portion.
11. A metal can body, comprising:
a sidewall portion that has at least one circumferentially
extending rib and a plurality of substantially longitudinally
extending ribs integrated therein, said circumferentially extending
rib providing additional strength to the sidewall portion, and
wherein said sidewall portion is configured in a non-cylindrical,
stylized shape, and wherein said circumferential extending rib and
said longitudinally extending ribs are positioned at locations of
said shaped sidewall portion that are anticipated to need increased
strength, wherein said longitudinal and circumferential ribs form a
gridwork of reinforcing cells in the sidewall portion that enhance
column strength, hoop strength, crush strength and pressure
strength.
12. A metal can body according to claim 11, wherein said
circumferentially extending rib and said plurality of
longitudinally extending ribs are each formed by an area of
increased thickness in said sidewall.
13. A metal can body according to claim 12, wherein said
circumferentially extending rib and said plurality of
longitudinally extending ribs each project radially inwardly from
said sidewall portion.
14. A metal can body according to claim 12, wherein said
non-cylindrical stylized shape of said sidewall portion comprises a
plurality of longitudinally extending grooves formed in said
sidewall portion, and wherein each of said thickened longitudinally
extending ribs are located in one of said grooves.
15. A method of making a metal can, comprising:
(a) forming a sidewall portion that has a plurality of
substantially longitudinally extending ribs, said longitudinal ribs
providing additional axial strength;
(b) assembling at least one can end member to said sidewall portion
to complete formation of a metal can; and
(c) forming the sidewall portion into a non-cylindrical, shaped can
at a point in time after step (a).
16. A can made according to the method described in claim 15.
17. A method according to claim 15, wherein step (a) comprises a
drawing and ironing process that is performed with a punch that has
a plurality of longitudinal grooves therein corresponding to said
ribs.
18. A method according to claim 15, wherein each of said
longitudinally extending ribs are formed by an area of increased
thickness in said sidewall.
19. A method according to claim 18, wherein each of said thickened
longitudinally extending ribs projects radially inwardly from said
sidewall portion.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to metal cans, such as those which are in
wide use for packaging soft drinks and other beverages. More
specifically, this invention relates to an improved metal can, and
especially a stylized, shaped can, that provides enhanced strength
characteristics at a given container weight as compared with
conventional metal containers.
2. Description of the Related Technology
Today's market for metal beverage cans is extremely price
competitive, which necessitates making the cans from the least
amount of metal possible while still providing the necessary
structural integrity to prevent collapsing or wrinkling the
container's side wall. Considering the enormous volume of cans that
are made worldwide each year, even a small reduction of the amount
of material that is necessary to provide a can of adequate strength
promises substantial cost savings to the industry. Accordingly, a
great deal of effort is being put into the development of metal
cans having improved strength to weight characteristics.
It has been proposed to manufacture two-piece can bodies with
circumferential, longitudinal or helical reinforcing ribs in order
to impart additional column or crush strength to the can body wall.
In particular, German published patent application DE 23 08 420
(1974) discloses formation of a can body with either helical and
longitudinal ribs by means of a standard drawing and ironing
technique wherein the punch is configured to create the additional
thickness of the reinforcing ribs. A similar invention was the
subject of published PCT application WO83/01916. U.S. Pat. No.
3,610,018 to Swanson et al. discloses manufacturing circumferential
reinforcement ribs into a steel can body in order to increase the
buckling resistance of a steel can.
Recently, there has been a great deal of interest in the can making
industry about the possibility of manufacturing so-called "shaped"
cans, which are configured to deviate from the standard "straight"
or cylindrical shape. A shaped can might be attractive to a
customer, for example, because it can suggest a beverage
manufacturer's distinctive glass or plastic bottle designs, or
other aesthetic or trade dress features. A shaped can is typically
made from a cylindrical metallic preform, which is shaped and sized
quite similarly to a standard straight or cylindrical can body. The
metallic preform is forced into the desired shape by one of a
number of different known methods, most of which use mechanical or
gaseous pressure, or some combination thereof. A complete
understanding of the deformation techniques for making shaped cans,
which are still evolving, is not critical to an understanding of
this invention.
Unfortunately, the shaping process tends to place a great deal of
strain on certain localized areas of the can preform. Furthermore,
any deviation from a cylindrical shape can reduce, among other
things, the axial strength of the can. In addition, shaped cans
tend to be more susceptible than straight cans to outward bowing or
other deformation such as when they are internally pressurized by
carbonation. The extent, location and type of deformation will
depend on the specific configuration of shaped can. For example,
one shaped can design with which the inventors are familiar has a
portion that includes broad, inwardly extending generally
longitudinal depressions or grooves which tend to be pushed
outwardly under pressure. The conventional thought would be that
this could and must be rectified by increasing the can's wall
thickness. Doing that, however, would add to the customer's
projected packaging expenses, making the can design less attractive
to the final customer, who is usually the soft drink manufacturer
or bottler.
A need exists in the industry for an improved metal can body and
method of making that provides additional strength and deformation
resistance to a can body, and especially to a shaped can body,
without adding substantial weight to the can body.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the invention to provide an
improved metal can body and method of making that provides
additional strength and deformation resistance to the can body,
without adding substantial weight to the can body.
In order to achieve the above and other objects of the invention, a
method of making a metal can, includes, according to one aspect of
the invention steps of (a) forming a sidewall portion that has a
plurality of circumferentially extending ribs integrated therein,
the ribs providing additional hoop strength to the sidewall
portion, and a plurality of substantially longitudinally extending
ribs, the longitudinal and circumferential ribs thereby forming a
gridwork of reinforcing cells in the sidewall portion; and (b)
assembling at least one can end member to the sidewall portion to
complete formation of a metal can.
According to another aspect of the invention, a method of making a
non-cylindrical shaped metal can body that is provided with a
stylized, irregular shape, includes steps of (a) forming a
substantially cylindrical sidewall portion that at least one
circumferentially extending rib integrated therein, the rib
providing additional strength to the sidewall portion; and (b)
shaping the cylindrical sidewall portion into a non-cylindrical,
stylized shape, and wherein the ribs are positioned at portions of
the shaped sidewall portion that are anticipated to need increased
hoop strength in order to withstand deformation under pressure,
whereby the shaped sidewall portion is reinforced against
deformation without increasing overall thickness of the
sidewall.
According to yet another aspect of the invention, a metal can
includes a sidewall portion that has a plurality of
circumferentially extending ribs and a plurality of substantially
longitudinally extending ribs in the sidewall, the longitudinal and
circumferential ribs forming a gridwork of reinforcing cells in the
sidewall portion that will enhance the strength of the sidewall
portion; and at least one can end member sealed to the sidewall
portion, whereby the can has superior strength characteristics when
compared to a can of like weight that does not possess such
circumferentially extending ribs.
In a further aspect of the invention, a metal can body includes a
sidewall portion that has at least one circumferentially extending
rib integrated therein, the rib providing additional hoop strength
to the sidewall portion, and wherein the sidewall portion is
configured in a non-cylindrical, stylized shape, and wherein the
rib is positioned at a portion of the shaped sidewall portion that
is anticipated to need increased hoop strength to withstand
deformation under pressure.
It has also been found that producing cans that have longitudinal
ribs extending inwardly from the inner surface of the can provides
additional strength and as a consequence permits the amount of
metal in the sidewall to be further reduced.
Finally another aspect of the invention comprises a metal can
includes a sidewall portion that has at least one circumferentially
extending rib integrated therein, the rib providing additional hoop
strength to the sidewall portion, and wherein the sidewall portion
is configured in a non-cylindrical, stylized shape, and wherein the
rib is positioned at a portion of the shaped sidewall portion that
is anticipated to need increased hoop strength to withstand
deformation under pressure; and at least one can end member sealed
to the shaped sidewall portion, whereby a metal can is formed that
is less likely to deform under the pressure of carbonation than a
can without such reinforcing ribs.
These and various other advantages and features of novelty which
characterize the invention are pointed out with particularity in
the claims annexed hereto and forming a part hereof. However, for a
better understanding of the invention, its advantages, and the
objects obtained by its use, reference should be made to the
drawings which form a further part hereof, and to the accompanying
descriptive matter, in which there is illustrated and described a
preferred embodiment of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 1A are a diagrammatical view of a method of
manufacturing a side wall for a can body or a shaped can preform
according to a first embodiment of the invention;
FIG. 2 is a cross sectional view taken through a reinforced can
that is made according to the process depicted in FIG. 1;
FIG. 3 is a side elevational view of a drawing and ironing punch
that is made for use in a process according to a second embodiment
of the invention;
FIG. 4 depicts a can body or preform that is made according to the
process using the drawing and ironing punch shown in FIG. 3;
and
FIG. 5 depicts a shaped metal can body that is made according to a
preferred embodiment of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Referring now to the drawings, wherein like reference numerals
designate corresponding structure throughout the views, and
referring first to FIGS. 1 and 1A, a can body or preform 10 for a
shaped can is depicted having a sidewall 12 along with a standard
assembly 14 for drawing and ironing a can body, the details of
which are well known in this area of technology. Assembly 14
includes a punch body 16 and one or more rings 18, as, again, is
well known in the industry. Can body or preform 10 is preferably,
although not necessarily, fabricated from aluminum.
According to a preferred embodiment of the invention that is
depicted in FIGS. 1, 1A and 2, the can body preform is manufactured
with at least one reinforced area 20, which is in the illustrated
embodiment a pair of circumferentially extending ribs in the
sidewall 12 of the can body or preform. As may be seen in FIG. 1,
the outer surface 24 of punch body 16 includes a pair of
circumferentially extending grooves 22 which allow formation of the
correspondingly shaped ribs 26 during the drawing and ironing
process. Ribs 26 impart additional strength to the sidewall of can
body/preform 12, which improves the vertical crush strength, the
lateral crush strength, and the strength against expansion due to
internal pressurization.
Looking to FIG. 2, a reinforced can 28 may be manufactured from the
sidewall of the can body/preform 12 by fastening a can end member
30 having an end panel 32 to the can body through a traditional
double seam type joint. The process for joining the can end member
30 to the can body is well known in the industry.
Referring now to FIGS. 3 and 4, the punch and the drawing and
ironing assembly 14 that is shown in FIG. 1 may alternatively be
embodied as a punch 36, shown in FIG. 3, that has, in addition to
the circumferentially grooves 22, of which there are three in the
embodiment of FIG. 3, a plurality of longitudinal grooves 38. A can
body/preform 40 that is manufactured by use of the punch 36 is
illustrated in FIG. 4. As may be seen in FIG. 4, can body/preform
40 includes a corresponding number of circumferentially reinforcing
ribs 26, and longitudinal reinforcing ribs 42. Longitudinal ribs 42
will enhance the vertical crush resistance of the container, which
is needed for, among other design reasons, to resist deformation
from axial compressive stresses that are applied during the
double-seaming operation. Ribs 42, 26 interact to form a plurality
of reinforcing cells 44, the combined effect of which substantially
strengthen the rigidity of the sidewall of the can body/preform 40
to an extent that the strength to weight ratio of the can
body/preform 40 exceeds that which was possible with a similarly
shaped and weighted cylindrical can body configuration. This
construction of the sidewall having the reinforcing cells 44, in
addition to increasing the strength to weight ratio, also increases
the puncture resistance of the can wall body, thereby permitting
additional lightweighting that would otherwise not be possible for
fear of susceptibility to puncturing.
A shaped metal can body 46 is depicted which will be recognized as
a design that is proprietary to a major soft drink manufacturer.
This particular shaped can design includes a number of inwardly
extending longitudinal oriented grooves 62, which, absent
reinforcement, tend to bow outwardly under pressure, thus making
the design substantially unworkable unless the wall thickness of
the can body is increased to an extent that would make the can body
economically unattractive to the potential customer. However, by
use of the invention, this area is adequately reinforced without
substantially increasing the weight of the can body. This is
achieved by strategically placing reinforced areas 48, 50, 52 at
portions of the shaped sidewall that are anticipated to need
increased hoop strength in order not to deform under pressure.
Reinforced areas 48, 50, 52 are, in fact, the areas which
correspond to the circumferential ribs 26 that are formed according
to either the embodiment of the invention that is depicted in FIG.
1 or that which is depicted in FIG. 4. Rib 26 translate, after
expansion of the can body into the shaped metal can body 46, into
ribs 54, 56, 58, respectively. The longitudinal reinforcing ribs 42
that are illustrated in the embodiment 40 may also be used to
reinforce the shaped metal 46, and appear as longitudinal ribs 62
that are shaped and placed strategically at areas of potential
weakness of the can body 46. The circumferential ribs 54, 56, 58
and the longitudinal ribs 60 together define a number of
reinforcement cells 64, which, as in the case of the preform/can
body 40 in the embodiment of FIG. 4, substantially increase the
strength of the shaped metal can body 46. After formation, the
shaped metal can body 46 may be assembly into a reinforce can in a
method that identical to that depicted in FIG. 2.
It has also been found that certain straight wall and shaped can
designs can be improved by the addition of longitudinal ribs 62
alone. Most preferably, the ribs 62 are arranged to extend inwardly
from the inner surface of the can body 46 so that the exterior
surface appears smooth and can be subsequently shaped. It will be
realized, however, that certain aesthetic benefits might be
realized by placing the ribs on the exterior surface and thus such
embodiments are within the scope of this invention.
It has been found that the use of longitudinal ribs alone increases
the strength of the can, particularly in terms of the ability to
resist axial loads. These benefits are realized whether the can has
a straight cylindrical wall, or is contoured.
Because the ribs described above add strength, it is now possible
to reduce the amount of metal in the sidewall. The inwardly
protruding ribs will preferably rise above thin areas of the
sidewall that are substantially wider than the ribs themselves.
An important feature, however, is again that the ribs may be
selectively placed to enhance the strength of the can in the areas
of greatest stress.
The thickness of the reinforcing ribs that are necessary to achieve
the benefits described hereinabove will depend on the specific
shape and application of the can body itself, as well as the can's
wall thickness. As an example, however, for a can having the shape
shown in FIG. 5, it is preferable to have a baseline wall thickness
of about 0.0041 inches, and for the vertical and circumferential
reinforcing ribs to add about another 0.001 to 0.002 inches of wall
thickness at the locations that are intended to be reinforced. This
results in a total sidewall thickness of about 0.005 to 0.006
inches at the location of the reinforcing ribs.
It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only, and changes may be made in detail, especially in
matters of shape, size and arrangement of parts within the
principles of the invention to the full extent indicated by the
broad general meaning of the terms in which the appended claims are
expressed.
* * * * *